<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box{
            width: 200px;
            height: 200px;
            margin: 100px auto;
            background-color: #ccc;
            font-size: 30px;
            color: #fff;

            /* text-shadow: 1px 1px 1px black, 2px 2px 1px black,
                        3px 3px 1px black, 4px 4px 1px black,
                        5px 5px 1px black, 6px 6px 1px black,
                        7px 7px 1px black, 8px 8px 1px black
                ; */
            /* 内边圆角, 边框直角 */
            border-radius: 10px;
            outline: 10px solid #000;
            box-shadow: 0 0 0 10px #000;
        }
        /* .box:hover{
            box-shadow: 0px 0px 0px 20px red;
        } */
    </style>
</head>
<body>
    <div class="box">
        Test
    </div>
</body>
</html>